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05 Jul 2018
German Geoscience Center Explains How Existing Data Cables Can Capture Seismic Signals
Optical fiber cables – including networks already deployed for communication purposes – may be used to detect earthquakes. other ground movements. Optical data cables can also pick up seismic signals from hammer blows, passing cars, or wave motions in the ocean.
Here are some of the significant findings of a study published in Nature Communications. His principal authors are Philippe Jousset and Thomas Reinsch from the German Geoscience Energy Systems (GFZ) GFZ Research Center for Geosciences in Potsdam, Germany. Scientists conducted the survey with colleagues from Iceland, the United Kingdom and Berlin, Germany
Scientists sent pulses of laser light through an optical fiber that was part of 39, a 15-kilometer cable deployed in 1994, in the telecommunications network of the Reykjanes Peninsula, southwest of Iceland, crossing an area of well-known geological faults in the rift between Eurasian and American tectonic plates [19659004] The light signal was analyzed and compared to a dense network of seismographs. Experts commented that the results "stunned" them.
"Our measurements revealed structural features in the subsoil with unprecedented resolution and signals equivalent to points every four meters," said Philippe Jousset of GFZ. He adds, "It's denser than any seismological network in the world."
After presenting preliminary ideas at several conferences since 2016, Jousset was informed that the new method was a "game changer for seismology". Although the method is not new in other applications (it has been used for years in drilling for reservoir monitoring), the team is the world's first to perform such measurements on the surface of the ground for seismological purposes.
Their current study shows not only well-known faults and volcanic dykes. Scientists have also found a loophole until then unknown, beneath the surface of the soil. In addition, the team measured subterranean deformations over a period of several minutes
Small local earthquakes, waves from large distant earthquakes and microseism of the seabed were also recorded by fiber cable optical. "We only need one strand of a modern optical fiber line," said Charlotte Krawczyk, director of GFZ's Geophysics Department
The advantages of the new method are huge because there are countless fiber optic cables in the dense world. telecommunication network. Especially in megacities with high seismic risks, such as San Francisco, Mexico City, Tokyo or Istanbul, and many others, such cables could be a cost-effective and widespread addition to existing seismic measurement devices.
Future studies are planned to determine whether submarine cables can also be used for seismic measurements. Scientists are optimistic. They think that the cables on the seabed will detect underwater earthquakes, ground movements of tectonic plates, as well as variations in water pressure. Therefore, the new method will help seismologists as well as oceanographers.
Stanford Project
By the way, in October 2017, Stanford University announced that researchers had built a quake observatory of a billion fiber optics. The university commented that "the same fiber optics that provide the Internet and HD video around the San Francisco Bay could serve as seismic sensors for earthquake monitoring."
The Stanford announcement said: "Thousands of kilometers of buried optical fiber crisscross the San Francisco Bay Area, California, providing high-speed Internet and HD video to individuals and businesses.
Biondo Biondi, professor of geophysics at the School of Earth Sciences, Energy and Environment Stanford, said he wanted to "transform the network of Dense Optical Fiber Optic Communication in an observatory of billions of sensors to continuously monitor and study earthquakes. "
Biondi added that his group has shown that it is possible to convert disturbed fiber optic strands into information about the direction and magnitude of seismic events." The researchers recorded these shocks seismic in a loop of three miles of optical fiber installed beneath the campus of Stanford University with instruments called laser interrogators provided by the company OptaSense, which is a co-author of publications on research.
We We can continually listen – and hear – the Earth by using pre-existing optical fibers that have been deployed for telecommunication purposes, "said Biondi
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